Methodological manuals have been worked out for the MINOTAVR®
digestion system with a detailed description of the destruction processes for such organic substances as meat and meat products; fish and fish products; milk and dairy produce; grains, groats, bread and bakery products; vegetables and fruits, natural, drinking and drain water, soft drinks, beer, alcoholic beverages, coffee and tea, etc.
The microwave field is produced by a magnetron with a power of 40 - 400 W and is delivered to a sample by a waveguide system.
The MINOTAVR® system is equipped with a pressure control unit which releases the excess gases hindering the digestion process and limiting the permissible weight of a sample in closed systems. This ensures the digestion to be complete and allows samples to be reduced to ash of 2 g dry weight. The heavier sample significantly relaxes the requirements for the sensitivity of the analysis technique, provides better representability of the sample, and improves the reproducibility of the analysis results. The higher degree of mineralization allows the sample to be prepared not only for the atomic absorption and atomic emission analyses (the sample being additionally reduced to ash), but also for the luminescent photometric and absorption analyses.
When being evaporated, the elements can be lost because of the sample overdrying, whereby some elements are converted into hardly soluble forms. In MINOTAVR®, the volume of the liquid residue is continuously monitored. When it reaches the given level, the device automatically turns to the after-evaporation mode, whereby the sample can be converted to the dry residue. The degree of evaporation is monitored by the reflected-to-absorbed microwave energy ratio.
MINOTAVR® reduces the effect of acids on the laboratory personnel to minimum, «heavy» acids being not used in the digestion process. The nitric acid vapor is removed via a condensate collector into an exhaust chamber or into a scrubber, where the acid is absorbed by an alkaline solution and the gaseous products by a solid-phase sorbent.
A container with the sample is always kept inside a protection housing with gas-removal ducts. The container can be removed from the device only after the pressure is released.
The protection from the microwave field effect is provided by a specially designed waveguide system, which rules out leaks outside the microwave module and is in full compliance with sanitary safety regulations in all the operation modes of the device.
Decomposition under and without pressure, evaporation, and extraction. Typically, mineralization takes 5 to 30 min, and evaporation less than 15 min, maximum liquid sample volume being 50 ml, and solid sample weight 2 g.